RASMUSSEN SYNDROME

OVERVIEW

This immune-mediated epilepsy is characterized by the onset
of intractable focal seizures (mainly focal
motor, commonly epilepsia partialis continua) together with
progressive hemiparesis in a previously
normal child. Progressive cognitive impairment may also develop. On
imaging, progressive hemiatrophy (of the side contralateral to the
hemiparesis) occurs over time. Pathology of brain tissue shows changes
of chronic encephalitis; the exact pathophysiology of this is unknown
(previous studies implicating certain viruses have not been
replicated), however there is sufficient evidence to support an
autoimmune basis.

Clinical context

This epilepsy is associated with onset of seizures between 1-10
years of age (peak 5-6 years), later onset is exceptional. Both sexes
are affected equally. Antecedent and birth history is usually normal.
Head size and neurological examination are usually normal prior to
onset of the epilepsy. With time, a progressive hemiparesis develops.
Some children may first present with a unilateral movement disorder
(hemidystonia, hemiathetosis) prior to onset of seizures. Iritis has
been reported as an antecedent condition. CSF may show non-specific
findings including the presence of oligo- or monoclonal bands. Medical
treatment is targeted at both seizures (anti-seizure medications) and
the underlying process (immunosuppression), ultimately most cases
require hemi-disconnection surgery to eliminate seizures. The timing
of such surgery is considered on a case-by-case basis and may depend
on the rate of progression and the cognitive impact of frequent
seizures.

There are three stages to the illness i) an initial prodromal
phase with infrequent seizures and no hemiparesis ii) an acute phase
with frequent seizures and development of hemiparesis and iii) a
residual stage with permanent stable hemiparesis.